J Clin Med Res

Journal of Clinical Medicine Research, ISSN 1918-3003 print, 1918-3011 online, Open Access

Article copyright, the authors; Journal compilation copyright, J Clin Med Res and Elmer Press Inc

Journal website https://jocmr.elmerjournals.com

Original Article

Volume 18, Number 6, June 2026, pages 369-378

Quantitative Facet Joint Effusion on Magnetic Resonance Imaging Is Associated With Dynamic Segmental Instability and Pain Severity in Degenerative Lumbar Spondylolisthesis

↓ Figure 2. Measurement of small joint effusion. Measurement of facet joint effusion width on axial T2-weighted MRI. The axial slice showing the largest facet joint space was selected and the maximal anteroposterior distance between opposing articular surfaces (white line/arrow) was measured perpendicular to the joint plane. The measured distance is reported as the maximum facet joint effusion width (mm). MRI: magnetic resonance imaging.

↓ Figure 3. ROC curves of facet joint effusion (FJE) width for predicting lumbar segmental instability. Left AUC = 0.9243; Right AUC = 0.9296 (P < 0.0001). AUC: area under the curve; ROC: receiver operating characteristic.

↓ Figure 4. Linear regression of slip ratio against facet joint effusion (FJE) width for the left and right sides. Fitted equations: Left, Y = 2.673X + 4.339; Right, Y = 2.759X + 4.357.

↓ Figure 5. Facet joint effusion (FJE) measurements in patients with lumbar segmental instability, comparing left and right sides with joint degeneration severity.

↓ **Table 1.** Grade of Lumbar Facet Joint Degeneration
Grade	Criteria
0	Normal facet joint width (2–4 mm)
1	Facet joint space narrowing, small osteophytes, and/or mild articular process hypertrophy
2	Facet joint space narrowing, moderate osteophytes, moderate articular process hypertrophy, and/or small subarticular bone erosions
3	Facet joint space narrowing, large osteophytes, severe articular process hypertrophy, subarticular bone erosions, and/or subchondral cyst formation

↓ Table 1. Grade of Lumbar Facet Joint Degeneration

Grade

Criteria

Normal facet joint width (2–4 mm)

Facet joint space narrowing, small osteophytes, and/or mild articular process hypertrophy

Facet joint space narrowing, moderate osteophytes, moderate articular process hypertrophy, and/or small subarticular bone erosions

Facet joint space narrowing, large osteophytes, severe articular process hypertrophy, subarticular bone erosions, and/or subchondral cyst formation

↓ **Table 2.** Baseline Characteristics of the Study Population by Lumbar Segmental Instability Status
Variable	Total (n = 151)	LSI unstable (n = 72)	LSI stable (n = 79)	P value
Values are presented as mean ± standard deviation (SD) or median (interquartile range, IQR) for continuous variables, and n (%) for categorical variables. Tests used: independent t-test for normally distributed continuous variables; Mann–Whitney U test (MW) for non-normal continuous variables; Pearson’s χ² test or Fisher’s exact test for categorical variables as appropriate. P values two-sided. max FJE: maximum facet joint effusion (mm); LSI: lumbar segmental instability (LSI = 1: unstable; 0: stable). For reproducibility: dataset variable names are max_FJE and instability_bin. BMI: body mass index; FJE: facet joint effusion; LSI: lumbar spine instability; VAS: Visual Analog Scale.
Age, years	64.52 ± 9.76	63.81 ± 8.47	65.16 ± 10.81	0.372
Sex, male, n (%)	33/151 (21.85%)	13/72 (18.06%)	20/79 (25.32%)	0.330
BMI, kg/m², mean ± SD	26.33 ± 4.20	27.42 ± 4.19	25.35 ± 4.00	0.002
Hypertension, n (%)	61/151 (40.40%)	36/72 (50%)	25/79 (31.65%)	0.030
Diabetes, n (%)	57/151 (37.75%)	32/72 (44.44%)	25/79 (31.65%)	0.077
Smoking, n (%)	17/151 (11.26%)	6/72 (8.33%)	11/79 (13.92%)	0.409
Alcohol, n (%)	13/151 (8.61%)	5/72 (6.94%)	8/79 (10.13%)	0.567
max FJE, mm, median (IQR)	1.16 (2.78)	2.81 (0.963)	0.00 (0.500)	< 0.001
FJE present, n (%)	88/151 (58.28%)	67/72 (93.06%)	21/79 (26.59%)	< 0.001
VAS, median (IQR)	3 (2)	5 (1)	3 (1)	< 0.001

↓ Table 2. Baseline Characteristics of the Study Population by Lumbar Segmental Instability Status

Variable

Total (n = 151)

LSI unstable (n = 72)

LSI stable (n = 79)

P value

Values are presented as mean ± standard deviation (SD) or median (interquartile range, IQR) for continuous variables, and n (%) for categorical variables. Tests used: independent t-test for normally distributed continuous variables; Mann–Whitney U test (MW) for non-normal continuous variables; Pearson’s χ² test or Fisher’s exact test for categorical variables as appropriate. P values two-sided. max FJE: maximum facet joint effusion (mm); LSI: lumbar segmental instability (LSI = 1: unstable; 0: stable). For reproducibility: dataset variable names are max_FJE and instability_bin. BMI: body mass index; FJE: facet joint effusion; LSI: lumbar spine instability; VAS: Visual Analog Scale.

Age, years

64.52 ± 9.76

63.81 ± 8.47

65.16 ± 10.81

0.372

Sex, male, n (%)

33/151 (21.85%)

13/72 (18.06%)

20/79 (25.32%)

0.330

BMI, kg/m², mean ± SD

26.33 ± 4.20

27.42 ± 4.19

25.35 ± 4.00

0.002

Hypertension, n (%)

61/151 (40.40%)

36/72 (50%)

25/79 (31.65%)

0.030

Diabetes, n (%)

57/151 (37.75%)

32/72 (44.44%)

25/79 (31.65%)

0.077

Smoking, n (%)

17/151 (11.26%)

6/72 (8.33%)

11/79 (13.92%)

0.409

Alcohol, n (%)

13/151 (8.61%)

5/72 (6.94%)

8/79 (10.13%)

0.567

max FJE, mm, median (IQR)

1.16 (2.78)

2.81 (0.963)

0.00 (0.500)

< 0.001

FJE present, n (%)

88/151 (58.28%)

67/72 (93.06%)

21/79 (26.59%)

< 0.001

VAS, median (IQR)

3 (2)

5 (1)

3 (1)

< 0.001

↓ **Table 3.** Multivariable Logistic Regression for Predictors of Lumbar Segmental Instability
Predictor	Coefficient (β)	SE	OR	95% CI	P value
Model: multivariable binary logistic regression with dependent variable LSI (unstable = 1, stable = 0). max FJE entered as continuous (mm). OR = exp(β). Model diagnostics performed: assessed linearity in the logit for continuous predictors, multicollinearity (variance inflation factor), goodness-of-fit (Hosmer–Lemeshow), and discrimination (AUC). BMI: body mass index; CI: confidence interval; FJE: facet joint effusion; OR: odds ratio; SE: standard error.
Intercept	−2.863	2.898	-	-	0.323
max FJE (per 1 mm)	1.825	0.268	6.20	3.67–10.48	< 0.001
Sex (male vs. female)	0.047	0.887	1.05	0.18–5.97	0.958
Age (per year)	−0.0078	0.031	0.99	0.93–1.05	0.801
BMI (per kg/m²)	0.0102	0.071	1.01	0.88–1.16	0.886
Hypertension (yes vs. no)	0.683	0.624	1.98	0.58–6.72	0.274
Diabetes (yes vs. no)	0.481	0.612	1.62	0.49–5.37	0.432
Smoking (yes vs. no)	−0.925	1.127	0.40	0.04–3.61	0.412
Alcohol (yes vs. no)	0.576	1.157	1.78	0.18–17.19	0.619

↓ Table 3. Multivariable Logistic Regression for Predictors of Lumbar Segmental Instability

Predictor

Coefficient (β)

95% CI

P value

Model: multivariable binary logistic regression with dependent variable LSI (unstable = 1, stable = 0). max FJE entered as continuous (mm). OR = exp(β). Model diagnostics performed: assessed linearity in the logit for continuous predictors, multicollinearity (variance inflation factor), goodness-of-fit (Hosmer–Lemeshow), and discrimination (AUC). BMI: body mass index; CI: confidence interval; FJE: facet joint effusion; OR: odds ratio; SE: standard error.

Intercept

−2.863

2.898

0.323

max FJE (per 1 mm)

1.825

0.268

6.20

3.67–10.48

< 0.001

Sex (male vs. female)

0.047

0.887

1.05

0.18–5.97

0.958

Age (per year)

−0.0078

0.031

0.99

0.93–1.05

0.801

BMI (per kg/m²)

0.0102

0.071

1.01

0.88–1.16

0.886

Hypertension (yes vs. no)

0.683

0.624

1.98

0.58–6.72

0.274

Diabetes (yes vs. no)

0.481

0.612

1.62

0.49–5.37

0.432

Smoking (yes vs. no)

−0.925

1.127

0.40

0.04–3.61

0.412

Alcohol (yes vs. no)

0.576

1.157

1.78

0.18–17.19

0.619

↓ **Table 4.** The Number and Amount of Joint Effusions in Segments With Segmental Instability of Slippage
Number of joint effusions (151)	LSI (72)	Non-LSI (79)	P
LSI: lumbar spine instability.
Left	66/72	17/79
Number
Effusions width (mm)	2.80 ± 0.90	1.31 ± 1.32	< 0.001
Right	66/72	18/79
Number
Effusions width (mm)	2.70 ± 0.88	1.20 ± 1.22	< 0.001
Bilateral	67/72	21/79
Number
Effusions width (mm)	2.75 ± 0.89	1.25 ± 1.25	< 0.001

↓ Table 4. The Number and Amount of Joint Effusions in Segments With Segmental Instability of Slippage

Number of joint effusions (151)

LSI (72)

Non-LSI (79)

LSI: lumbar spine instability.

Left

66/72

17/79

Number

Effusions width (mm)

2.80 ± 0.90

1.31 ± 1.32

< 0.001

Right

66/72

18/79

Number

Effusions width (mm)

2.70 ± 0.88

1.20 ± 1.22

< 0.001

Bilateral

67/72

21/79

Number

Effusions width (mm)

2.75 ± 0.89

1.25 ± 1.25

< 0.001

↓ **Table 5.** Grading of Small Joint Degeneration and Amount of Joint Effusion
Grade	Number of FJE/degenerated joints	Effusions width (mm)	VAS
FJE: facet joint effusion; VAS: Visual Analog Scale.
1	Left	18/21	2.49 ± 0.84	3.77 ± 0.99
	Right	18/34	2.07 ± 1.27
2	Left	37/58	2.84 ± 1.42	3.86 ± 1.29
	Right	50/62	2.73 ± 0.96
3	Left	28/62	2.04 ± 0.76	3.44 ± 1.16
	Right	16/55	1.62 ± 1.05

↓ Table 5. Grading of Small Joint Degeneration and Amount of Joint Effusion

Grade

Number of FJE/degenerated joints

Effusions width (mm)

VAS

FJE: facet joint effusion; VAS: Visual Analog Scale.

Left

18/21

2.49 ± 0.84

3.77 ± 0.99

Right

18/34

2.07 ± 1.27

Left

37/58

2.84 ± 1.42

3.86 ± 1.29

Right

50/62

2.73 ± 0.96

Left

28/62

2.04 ± 0.76

3.44 ± 1.16

Right

16/55

1.62 ± 1.05